It is well known in the art that the nematoda disease of rice is a wide-spread disease of rice and it causes the greatest losses of the crop (20-60%) in the countries situated in the temperate zone. (Hashioka, Y.: Nematoda Diseases of Rice in the World, l1 Riso, Milano, 1964; Economic Nematology, 1972, Academic Press, London-New York; Rice Diseases, Commonwealth Mycological Inst., Kew, Surrey, England, 1972).
the symptoms of the said disease were observed only at the end of the 1960, i.e. the discovery of the spreading of leaf nematoda causing the disease and the search for the processes suitable for avoiding said disease were started at that time in Hungary. (Javor, I.: The Spreading of Rice Nematoda, Damage of the Same and the possibilities of Control, Novenyvedelem, 1973, 9. 2.) The first great damage of the crop which could be attributed to nematoda was observed on the Dubouszki-129 species of rice.
In the highly infected (in some locations) fields the loss of crop was 50-60%.
In the same year similar symptoms were observed on other species as well. The nature of the infection was investigated on these crops and several attempts were made to work out suitable methods for the treatment and prevention of the infection. (Taylor, A. L.: Report About Nematoda Problem of Rice at the Hungarian Rice Production, 1976; Mrs. Simon: Novel Rice Disease: Nematoda Disease of Rice, MEM Informecios Kozpont, No. 156)
The rice leaf nematoda (Aphelenchoides besseyi Christie) causes the disease of rice, which spreads (in inactive state) mainly with the seed.
The most suitable manner for controlling this disease is the prevention, i.e. the use of nematoda-free seed, as the spreading of the disease could be inhibited with great difficulty and would cause great expense.
A known method for making nematoda-free seeds is the treatment with warm (52.degree.-53.degree. C.) water, but this method is not suitable for the treatment of seeds of large scale.
Some chemicals were also suggested for this purpose, however, as they are harmful and damage the plant embryo, they are not used in agricultural practice.
It can be stated that there is no suitable method for the prevention of nematoda disease which could be applied on a large scale.
Our aim was to eliminate the drawbacks of the known methods and to work out a process which the seeds, especially rice can simply be disinfected on large scale with good efficiency.